Method of preparing GaN monocrystal substrate in mechanical removal way

Abstract

The invention discloses a method of preparing a GaN monocrystal substrate in a mechanical removal way. A thin film of layered structure is pre-deposited between a GaN monocrystal thick film and a substrate and the GaN monocrystal thick film and the substrate are separated in a horizontal sliding mode to obtain a complete large size self-supporting GaN monocrystal substrate by utilizing the fact that the van der Waals force of the film of layered structure between the substrate and the GaN monocrystal thick film is weak and easy to slip. According to the method of preparation GaN monocrystal substrate in a mechanical removal way, a low-cost preparation method is utilized to obtain the self-supporting GaN monocrystal substrate which is smooth in surface without cracks and high-quality in crystal, the controllable separation of the GaN monocrystal thick film and the heterogeneous substrate is achieved with simple device with no need of other complex technology devices like the laser lift-off and the lithography etching nanometer graphics and no need of in situ etching or laser lift-off components in the reaction chamber, and the process stability, easy control and application to industrial production can be obtained.

Description

technical field [0001] The invention relates to the field of optoelectronic materials and devices, in particular to a method for preparing a gallium nitride single crystal substrate through a mechanical removal method. Background technique [0002] Gallium nitride GaN-based III~V nitrides are important wide-bandgap semiconductor materials with direct bandgap. It has broad application prospects in fields such as power electronic devices and other optoelectronic devices and electronic devices, as well as semiconductor devices under special conditions. [0003] Due to the extremely high melting temperature and high nitrogen saturation vapor pressure, it is very difficult to prepare large-area GaN single crystals, and GaN-based devices have to be grown heterogeneously on sapphire or silicon carbide substrates with large mismatches. Although this heteroepitaxy technology based on buffer layer technology has achieved great success, this method cannot give full play to the superio...

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Problems solved by technology

[0003] Due to the extremely high melting temperature and high nitrogen saturation vapor pressure, it is very difficult to prepare large-area GaN single crystals, and GaN-based devices have to be grown heterogeneously on substrates such as sapphire or silicon carbide with large mismatches.

Although this heteroepitaxy technology based on buffer layer technology has achieved great success, this method cannot give full play to the superior performance of GaN-based semiconductor materials. The main problems are: 1. Due to the large gap between GaN and sapphire The lattice mismatch and thermal stress mismatch, resulting in 10 9 cm -2 The misfit dislocations seriously affect the crystal quality and reduce the luminous efficiency of LED; 2. Sapphire is an insulator, and its resistivity is greater than 10 at room temperature. 11 Ωcm, so that it is impossible to make a device with a vertical structure, usually only N-type and P-type electrodes can be made on the upper surface of the epitaxial layer, so the effective light-emitting area is reduced, and the photolithography and etching process in the device preparation is increased. Reduce the utilization rate of materials; 3. The thermal conductivity of sapphire is not good, and the thermal conductivity at 100°C is about 0.25W / cm K, which has a great impact on the performance of GaN-based devices, especially in large-area and high-power devices 4. In the production of GaN-based lasers, due to the high hardness of sapphire, and there is a 30-degree angle between the sapphire lattice and the GaN lattice, it is difficult to obtain the GaN-based LD epitaxial layer. Therefore, the GaN single crystal substrate is also of great significance to the fabrication of GaN-based lasers.

However, these methods have disadvantages such as complicated equipment, difficult separation, easy breakage of GaN single crystal thick film, and low yield, which makes the price of GaN single crystal substrate remain high.

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